Gale Warning 386, NWS Anchorage, AK

SOUTH CENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT MON MAY 9 2011

.MODEL DISCUSSION...

THE LOW OVER THE BRISTOL BAY AND EASTERN AK PENINSULA AND ASSOCIATED
FRONT INTO THE WESTERN GULF ARE ON TRACK MOVING SOUTHEAST. A SECOND
LOW SOUTH OF THE MAIN CENTER IS PICKED UP IN THE MODELS AS WELL AS IS
A FRONTAL TRIPLE POINT LOW EAST SOUTHEAST OF KODIAK. THE MODELS ARE
ALSO DOING WELL WITH RESPECT TO THE SYSTEM NEAR THE KAMCHATKA
PENINSULA AND ITS ASSOCIATED FRONT.

.ANALYSIS AND UPPER LEVELS...

THE SURFACE AND UPPER LEVEL LOW OVER THE ASTERN AK PENINSULA IS
MOVING EAST SOUTHEAST TOWARD THE COMPLEX LOW PRESSURE OVER THE GULF
OF ALASKA. THIS IS A GOOD COLD CORE LOW OVER RELATIVELY COOL LOW
LEVEL AIR SUPPORTING A SOMEWHAT UNSTABLE ENVIRONMENT THAT IS
CONVECTIVE AS EVIDENT IN THE SATELLITE IMAGERY. THE MILDLY UNSTABLE
AIR IS ALSO IN ALONG THE NORTH GULF COAST SUPPORTING FREQUENT SHOWERS
IN PRINCE WILLIAM SOUND AND THE EASTERN KENAI PENINSULA. THE INFLUX
OF COLD AIR ALOFT WILL SUPPORT THE DEVELOPMENT AND INTENSIFICATION OF
THE CONSOLIDATED LOW IN THE CENTRAL GULF OVERNIGHT TONIGHT. OVER
SOUTHWEST ALASKA THE BRISTOL BAY ZONE IS THE MOST ACTIVE WITH RESPECT
TO SHOWERY ACTIVITY AND SHOWERS ARE ALSO EXTENDING BACK TO THE WEST
TO THE DUTCH HARBOR AREA IN THE NORTHWEST FLOW. FURTHER INLAND THE
NORTHEAST TO NORTH FLOW IS DRYING THE REGION AND CLEARING THE CLOUDS
OUT OF THE LOWER KUSKOKWIM VALLEY AND KUSKOKWIM DELTA.

THE SURFACE AND UPPER LEVEL RIDGE NOW OVER THE CENTRAL ALEUTIANS TO
THE CENTRAL BERING SEA WILL CONTINUE MOVING EAST THEN STALL OVER THE
EASTERN BERING AND FAR WESTERN ALASKA MIDWEEK.

THE WELL DEFINED FRONT NOW AFFECTING THE WESTERN ALEUTIANS IS
PRODUCING SUB GALE FORCE WIND. THE WIND IN ADVANCE OF THE FRONT IS
EXPECTED TO INCREASE AS THE FRONT PUSHES INTO THE WESTERN ALEUTIANS
LATER THIS EVENING. THE EASTWARD PROGRESSION OF THE FRONT WILL SLOW
AS IT PUSHES AGAINST THE RIDGE THROUGH TUE MORNING.

.SHORT TERM FORECAST...

SOUTH AND EAST OF THE ALASKA RANGE...
A AS THE LOW IN THE GULF INTENSIFIES TONIGHT IN THE GULF THE NORTH
WINDS WILL BEGIN INCREASING AS THE PRESSURE GRADIENT INCREASES ALONG
THE GULF COAST. COUPLED WITH THE ARRIVAL OF A NORTHERLY JET STREAK ON
TUESDAY WINDS WILL INCREASE ACROSS THE SUSITNA VALLEY AND WESTERN
KENAI PENINSULA. THE DRYER AIRMASS COUPLED WITH THE GUSTY NORTH WINDS
WILL BRING UP FIRE WEATHER CONCERNS OVER THE SOUTH CENTRAL REGION TUE
AND WED.

AS THE LOW IN THE GULF TRACKS SOUTHEAST IT WILL RESULT IN CUTTING OFF
THE MOIST EAST FEED ALONG THE COAST PUTTING AN END TO THE SHOWERS BY
TUE.

OVERALL MUCH DRIER CONDITIONS ARE EXPECTED THROUGH LATE WEEK AFTER
THIS CURRENT SYSTEM MOVES OUT OF MOST AREAS TONIGHT.

SOUTHWEST ALASKA...

RAIN SHOWERS WILL SLOWLY DECREASE IN COVERAGE THROUGH THIS EVENING IN
BRISTOL BAY ZONE.EXPECT A GENERAL CLEARING AND WARMING TREND AS THE
RIDGE OVER THE BERING MOVES TO THE BERING COAST THROUGH WED MORNING.

BERING SEA/ALEUTIANS...

A SERIES OF FRONTS WILL TRACK ACROSS THE WESTERN BERING ON THE
UPSTREAM SIDE OF THE HIGH PRESSURE AND BRING A RETURN TO UNSETTLED
WEATHER ALONG WITH SOME STRONGER WINDS. THE GUSTY NORTHWEST WIND
ACROSS THE EASTERN ALEUTIANS AND AK PENINSULA WILL GRADUALLY IMPROVE
AS HIGH PRESSURE MOVES EAST ACROSS THE AREA. THE STRENGTH OF THE HIGH
PRESSURE RIDGE ALOFT ALONG WITH THE COLD SEA SURFACE TEMPERATURES
WILL LIKELY KEEP LOW STRATUS OVER MUCH OF THE AREA.

A LARGE COMPLEX LOW PRESSURE SYSTEM BETWEEN THE WESTERN ALEUTIANS AND
THE KAMCHATKA PENINSULA WILL ROTATE DISTURBANCES NORTH AND EAST
ACROSS THE WESTERN TO CENTRAL ALEUTIANS TONIGHT THROUGH MIDWEEK
BRINGING AN INCREASE IN WINDS TO GALE FORCE AS WELL AS PERIODS OF
RAIN.

.LONG TERM FORECAST...

BY THE WEEKEND THE UPPER LEVEL RIDGE OVER THE SOUTHERN MAINLAND WILL
WEAKEN AND FLATTEN TO THE SOUTH AS A LARGE BROAD UPPER LEVEL LOW OVER
THE BERING SETS UP COOL MOIST SOUTHERLY FLOW INTO THE SOUTHWEST
MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WARNING AND FLOOD WATCH...152
MARINE...GALES...150 170 175 176
FIRE WEATHER...NONE.

SAM MAY 11